Assessment of Prematurity by Birth Weight , Crown - Rump Length , and Head Circumference by Richard

In view of the importance now attached to the care of the premature infant, it is highly desirable that stock should be taken of the definitions and classifications in general use, and that the possibility of their improvement should be frequently reviewed. Whilst it is generally recognized that the prospects of survival depend to a much greater extent on functional maturity, e.g. of respiration, digestion, and temperature regulation than they do on any single body measurement, it is likely that objective measurement will always play a certain part in the assessment of both full term and premature infants. In the classification of prematures for record purposes and for comparison of results obtained in different clinics, objective measurement is still essential. To be of service to the clinician, such measurements must be ones, which may be made on the living infant with reasonable accuracy, and ones which do not involve dangerous exposure or manipulation. Those which can readily be applied in the home bynursing personnelwill haveawider application than those requiring specialized techniques or apparatus, though these latter may prove of greater value under hospital conditions. A vast amount of data on measurements of premature infants has already accumulated. Scammon and Calkins (1929) who reviewed much of the earlier literature and added some thousands of personal observations, estimated that at least 160,000 measurements had been published up to that time, relating to more than 100 body measurements. It may at first appear surprising that relatively little of this data has been generally used by clinicians for the assessment of prematurity, and that in the majority of clinics birth weight remains the sole or major criterion for classification. Further examination of the data, much of which derives from post-mortem examination, however, at once emphasizes the differences between examination of living infants and those which have been preserved, injected or at least rendered permanently immobile. Foot-length, for example, which Streeter (1920) found useful as an additional control of gestational age, does not lend itself to accurate measurement in the living infant, whilst circumferential measurements of chest and abdomen are affected by respiration, abdominal distention and movement to an extent which introduces a considerable error. Nevertheless disproportion between head and chest circumference is sometimes taken as an additibnal indication of prematurity (Reiche, 1916; Dunham, 1948). With regard to head measurements, which will be considered further, it must be remembered that necropsy material examined by pathologists and anatomists is likely to be heavily weighted by stillbirths or birth-deaths in which a greater degree of head moulding or cranial damage is to be expected than in living infants. Perhaps most important of all, much of the published data is related to a single measurement (e.g. total height or crown'heel length), and the estimate of gestational age is often arbitrary, or based on criteria which would no longer be regarded as wholly acceptable.